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    Rhodamine 6G and Au–Pd core–shell nanorods: Fluorescence enhancement for detection of mercury
    (2018-01-01)
    Rammarat, Ekkachai
    ;
    Kraithong, Sasiwimon
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    Wanichacheva, Nantanit
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    Swanglap, Pattanawit
    ;
    We show that hybrid organic–inorganic particles are efficient for accurate sensing of mercury ions and following up trace amounts of the mercury pollutions spread in the environment. The process of synthesis of a working substance starts from preparation of rhodamine 6G derivative. Then the dye molecules are bound on the surface of Au–Pd core–shell nanorods. Mercury ions with different concentrations are finally attached onto this fluorescence sensor. Fluorescence emission of the sensor is detected with a luminescence spectrophotometer. The experimental results demonstrate that the fluorescence intensity of one of our sensors, a sensor B, is remarkably enhanced when the mercury-ion concentration increases from 0 to 15.5 µM. The limit of detection of the ions is as low as 20.6 nM. The working mechanism of our fluorescence sensor can be explained through the fluorescence-energy transfer and the plasmonic effect associated with spirolactam forms of rhodamine and conducting bimetallic nanoparticles.
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    Enhancement of fluorescence in inorganic dyes by metallic nanostructured surfaces
    We have studied the influence of shape and chemical content of metallic nanostructures (gold-palladium core-shell nanorods, gold nanobipyramids and single-crystalline porous palladium nanocrystals) on the luminescence of Rhodamine 6G and Coumarin153 dyes. The changes found in the emission intensity are attributed to different proportions of the dyes and the metallic nanostructures. The enhancement of the fluorescence observed by us for the cases of Rhodamine 6G with gold-palladium core-shell nanorods and Rhodamine 6G with gold nanobipyramids suggests their promising plasmonic properties. This may be regarded as a preliminary step towards development of the fluorescent probes possessing high photo-sensitivity.
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    Superhydrophobilization of SiO2 surface with two alkylsilanes for an application in oil/water separation
    (2018-04-01) ;
    Pasupong, Patchara
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    ;
    This study reported a novel approach to superhydrophobilize silica (SiO<inf>2</inf>) surface by silanizing with two alkylsilanes including non-polar short hydrocarbon chains of chlorotrimethylsilane (CTMS) followed by long hydrocarbon chains of octadecyltrichlorosilane (OTS). The silanization of CTMS prior to OTS affected the increase in the density of short and long alkyl chains throughout SiO<inf>2</inf> surface resulting in the surface with low surface energy and high degree of hierarchical micro-nanoscale roughness which were responsible for the superhydrophobicity. The oil/water separation filters prepared by coating cotton fabric with the CTMS- and OTS-modified SiO<inf>2</inf>/polystyrene (PS) composite using a weight ratio of the modified SiO<inf>2</inf>:PS at 2:1 possessed the highest water contact angles of 156° ± 1°. The superhydrophobic/superoleophilic filters showed excellent water repellent, oil/water separation efficiency, and reusability. The results obtained in this study suggest that salinizing the two different structure alkylsilanes, CTMS followed by OTS, can provide synergetic benefit in improving the superhydrophobicity by enhancing the density of alkyl chains on SiO<inf>2</inf> surface. This alternative strategy can be extensively applied for development of other superhydrophobic materials.
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    Effects of gold nanoparticles on fluorescence polarization and emission spectra of rhodamine 6G solution
    (2018-01-01) ;
    Rammarat, Ekkachai
    ;
    Fluorescence polarization and emission spectra of Rhodamine 6G solution with gold nanoparticles have been studied. It is found that the emission intensities tend to be low when the gold nanoparticles are added into the solution partly due to the energy transfer from the Rhodamine 6G to gold nanoparticles. The fluorescence polarization increases as the concentration ratio of the gold and Rhodamine 6G is more than 124 and decreases as the ratio is about 1115. The enhancement and reduction of fluorescence polarization values are understood as the shortening of the fluorescence lifetime and a temperature effect from the heating of gold nanoparticles, respectively.
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    Microwave-activated reduced graphene oxide composite with hydrothermally treated corn husk activated carbon as an active electrode for high electrochemical performance in symmetrical carbon-based supercapacitor devices
    (2026-07-01)
    Srakaew, Khattiya
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    Ratchayotee, Pornthip
    ;
    Janorat, Phattharawadee
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    This work applies microwaves for synthesizing reduced graphene oxide (rGO) and waste material corn husk activated carbon composites as active electrode materials for symmetric supercapacitors. The rGO is activated by microwave treatment and corn husk carbon by KOH in processed hydrothermal activation, followed by compositing at various weight ratios. Among all compositions, rGO:H_Corn_C (90:10) is reported with the best properties, with a specific surface area of 314.2 m2/g and a high specific capacitance of 1152 F/g at 0.1 A/g. The optimized composite also delivered increasing energy and power densities of up to 160 Wh/kg and 9.68 × 102 W/kg, respectively, within a 1 V operating window. In an experiment by assembling a symmetric coil cell supercapacitor, the device showed a specific capacitance of 142.23 F/g at 0.1 A/g, cycling stability with 98.8% capacitance retention after 1000 cycles of charge-discharge, and peak energy and power densities of 40.68 Wh/kg and 5.74 × 102 W/kg. Overall, the composite material with a high content of rGO and corn husk-derived activated carbon prepared by the hydrothermal method exhibits high-performance for the material in supercapacitor applications.
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    Apparatus for inspection of low-coercivity magnetic force microscopy tips
    (2018-08-13)
    Damrongsak, Badin
    ;
    Photaram, Worachote
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    Saengkaew, Karnt
    ;
    Cheowanish, Ittipon
    ;
    In hard disk drive manufacturing, magnetic force microscopy (MFM) is employed to provide feedback for process control. This requires accurate and precise measurement of the intensity and the width of the write field generated from fabricated recording heads. Thus, the response of MFM tips when exposed to the write field must be consistency, run to run and machine to machine; however, no specific tool that can inspect and separate out-of-spec or defective MFM tips is available so far. In this present work, we designed and developed a new apparatus that is suitable to quantitatively evaluate the performance of low-coercivity MFM tips. The detailed discussion of the design of the proposed system is given as well as the inspection algorithm. Basically, a solenoid coil is used as a magnetic field generator which can generate the field strength up to 500 Oe, enough to saturate the tip magnetization. When the tip was exposed, a phase difference of the oscillating MFM tip, which is directly proportional to the field intensity, is employed as a measure of the tip response. In addition, the capability of the implemented apparatus to inspect low-coercivity MFM tips was demonstrated. Results were then compared with those obtained from a conventional MFM machine with the reference magnetic write head as a test sample. Several tests with different sets of low-coercivity MFM tips were carried out to evaluate the implemented system. Results showed that it can distinguish the response of different MFM tips; however, as the results were not too different, only three samples were selected to present here, including the tips with typical magnetic response, low response and out-of-spec response. The measured phase shifts of those samples were 54.5 ± 0.3, 36.3 ± 0.3 and 15.4 ± 0.2 degrees, respectively.
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    Optical imaging of artificial latent fingerprints using rhodamine 6G and au-core/Pd-shell nanorods
    Latent fingerprints represent valuable information-storage platforms, which play a key role in the forensic practice and health assessment. Recent works have explored novel image-enhancement methods in latent fingerprinting, which are associated with fluorescence dyes. In this study we improve the quality of fingerprint images, using a combination of fluorescence dyes and bimetallic nanoparticles. We find that Rhodamine 6G can serve as a kind of ‘glue’ adhering well onto Au–Pd core–shell nanorods. This system which employs molecules like α- amylase can be successfully used for recognition of artificial latent fingerprints. The appropriate mechanism can be coupling of localized surface plasmon resonance in the nanorods mentioned above and the emission of Rhodamine 6G. As a result, we observe notable enhancement of the images of artificial latent fingerprints.
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    The electrochemical measurements investigation of NiCo2O4for electrode materials of energy storage devices by using digital holography technique
    (2021-01-01)
    Prakobsang, Tawipon
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    Saei, Worawee
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    Kongsubto, Thee
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    ;
    The electrochemical properties of NiCo2O4for using as electrode materials for the potential applications have been investigated by electrochemical measurement which composed of cyclic voltammetry (CV) and galvanostatic chargedischarge (GCD). These processes are generating the ion exchange between the electrode and electrolyte, wherein induce the surface change of the interface. Especially, since in the cycle ability measurement using the potentiostat needed to repeat the cycle into the electrode for many times, the effective of the electrode is reduced. In this research, digital holographic technique was used to investigate the different properties of interface of the NiCo2O4 electrode while operating under the various electrochemical techniques. In our DH recording, the surface change of the electrode was expose at the difference potential scan rate at 1, 5, 10, 50, 100 and 200 mV/s of CV, and the difference current densities at 1, 2, 3, 5, 10 and 20 A/g of GCD and vary times of cycle ability test every 50 cycle times to 1000 cycles. In the end the reconstructed DH images of the electrode have been used to analyze the results from electrochemical measurement.
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    Antitumor activities of carboplatin–doxorubicin–ZnO complexes in different human cancer cell lines (breast, cervix uteri, colon, liver and oral) under UV exposition
    (2021-01-01)
    Pairoj, Suttirak
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    Damrongsak, Badin
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    Jinawath, Natini
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    Kaewkhaw, Rossukon
    This study aimed to examine the pharmacological profiles of multiple chemo drug candidates in systematic circulation to enhance their specific interactions with five human cancer cell lines. ZnO nanoparticles were successfully bound with chemo drugs via physical adsorption. The drug loading capacity was confirmed by FTIR, whereas the loading efficiency was determined via UV–vis spectrometry. The mean hydrodynamic size increased to 69–82 nm after chemo-drug immobilization via non-covalent interaction with ZnO. Among the nine formulated chemo drugs, the carboplatin (CP)–doxorubicin (DOX)–ZnO complex under UV light irradiation exhibited high sensitivity towards human breast adenocarcinoma cells without affecting human keratinocyte immortal cells with an IC<inf>50</inf> of 0.137 µg/mL, whereas the loading capacity and efficiency of CP–DOX–ZnO were 77.81% and 99.05%, respectively. Fluorescence images confirmed that CP–DOX–ZnO using DOX served as a fluorescence enhancer specifically bound onto the cell membranes, which became almost saturated after 24 h incubation. Carboplatin–DOX–ZnO was possibly endocytosed by cancer cells and was selectively internalized into the target cells; thus, free chemo drug was released in the cytoplasm, which induced acute apoptosis. This resulted in complete inhabitation of growth signal of target cancer cells.
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    Implementation of a Measurement System for Inspection of Magnetic Force Microscopy Probes
    (2017-10-20)
    Phanchat, N.
    ;
    Saengkaew, K.
    ;
    Cheowanish, I.
    ;
    ;
    Damrongsak, B.
    A non-destructive measurement system for the inspection of magnetic force microscopy (MFM) probes was implemented and discussed in this paper. Its operating system was similar to that used in standard AFM/MFM machines. The MFM probe under test was held on a sample holder and was oscillated by a piezoelectric transducer. The oscillation of the MFM probe was measured by an optical beam deflection technique. In order to measure a response of the MFM probe under the presence of magnetic fields, a solenoid coil was employed as a source for generating the out-of-plane magnetic field. This avoids physical contact which may damage the MFM probe. Different types of MFM probes, including commercial probes and developed in-house probes with different coating thicknesses, were used to demonstrate the system. Experiments revealed a promising result and showed the dependence of the probe sensitivity on the coating thicknesses.